This mulberry jam recipe uses an overnight maceration (soaking time) and homemade pectin to keep the sugar amount moderate and the cooking time low.
Mulberries are a low pectin fruit, which means that they don't gel well on their own. But adding commercial pectin often requires adding huge amounts of sugar. The alternative is a super long cooking time.
This recipe is an excellent way to make mulberry jam without having to buy pectin or rely on heavy sugar content or long cooking times that result in loss of flavor and color.
Mulberries don't all ripen at the same time, which is one of the reasons you'll rarely see them as a commercial crop. An easy way to harvest them is to lay down a ground cloth and shake the lower branches of the tree. The ripe berries will fall off.
Even very ripe mulberries usually come off of the tree with a little bit of stem attached. It is fiddly work to remove the little stems, and you don't have to. It's up to you whether to take the time for that job, but if you do your jam will have a better texture.
- Put the mulberries into a large non-reactive pot. That means no un-enameled cast iron, aluminum, or copper, which could result in a dark, discolored jam. Enameled pots, stainless steel, and Pyrex or other heat-proof glass are fine.
- Add the sugar and mix well. Cover and refrigerate for 8 hours or overnight. This long maceration reduces the cooking time later, resulting in a fruitier, more brightly flavored and colored jam.
- Sterilize the canning jars by immersing them in boiling water for 15 minutes. Do not boil the canning lids but rather drop them into the hot water with the jars after you have turned off the heat.
- The mulberries will have released a lot of their juice during their maceration. Stir the macerated berries and their juice to liquefy any still-undissolved sugar.
- Stir in the homemade pectin and the lemon juice or cider vinegar.
- Place the pot with the mulberry mixture over high heat and cook, stirring frequently, until the mixture reaches the gel point.
- Ladle the jam into the sterilized jars, leaving 1/2-inch head space between the surface of the jam and the rims of the jars. Wipe off the rims of the jars with a clean, damp cloth or paper towel. Screw on the canning lids.
- Process in a boiling water bath for 5 minutes (adjust the canning time if you live at a high altitude).
The sealed jars can be stored at room temperature, but once opened, keep them in the refrigerator just as you would with store bought jam. Sealed, your mulberry jam will keep for 1 year. The jam is still safe to eat after that, but the quality declines.